scc

commit a3a90734a04b065b429ab4810068a4f74386272e
parent d3f6fa971de7cee49a877f2ea8d8049cc726273d
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Thu,  9 May 2019 13:41:59 +0100

[dev] Add memrchr

Diffstat:
M
include/string.h
 | 
1
+
M
src/libc/string/Makefile
 | 
1
+
A
src/libc/string/memrchr.c
 | 
13
+++++++++++++

3 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/include/string.h b/include/string.h
@@ -19,6 +19,7 @@ extern int strcoll(const char *s1, const char *s2);
 extern int strncmp(const char *s1, const char *s2, size_t n);
 extern size_t strxfrm(char * restrict s1, const char * restrict s2, size_t n);
 extern void *memchr(const void *s, int c, size_t n);
+extern void *memrchr(const void *s, int c, size_t n);
 extern char *strchr(const char *s, int c);
 extern size_t strcspn(const char *s1, const char *s2);
 extern char *strpbrk(const char *s1, const char *s2);
diff --git a/src/libc/string/Makefile b/src/libc/string/Makefile
@@ -4,6 +4,7 @@ include $(PROJECTDIR)/scripts/rules.mk
 include ../rules.mk
 
 OBJS = memchr.o\
+       memrchr.o \
        memcmp.o\
        memcpy.o\
        memmove.o\
diff --git a/src/libc/string/memrchr.c b/src/libc/string/memrchr.c
@@ -0,0 +1,13 @@
+#include <string.h>
+
+#undef memrchr
+
+void *
+memrchr(const void *s, int c, size_t n)
+{
+	unsigned char *p = s;
+
+	for (p += n-1; n > 0 && *p != c; --p)
+		n--;
+	return (n == 0) ? NULL : p;
+}